The Arteriosclerosis SCOR at Columbia comprises a multidisciplinary and coordinated set of clinical and laboratory research activities within the broad field of arteriosclerosis research. The SCOR program includes projects directed at major questions in the areas of lipid metabolism, hyperlipidemia, atherosclerosis, thrombosis, and coronary heart disease. A central focus of this program is the detailed and extensive study of patients with hyperlipidemia. The major ongoing projects include studies of: (1) cholesterol turnover and metabolism in man; (2) vitamin A transport in plasma; (3) platelet-derived growth factor and the regulation of the growth of human arterial smooth muscle cells; (4) regional myocardal perfusion in patients with coronary atherosclerosis; (5) intravascular coagulation and thrombosis in patients with hyperlipidemia; (6) metabolism of the various plasma apolipoproteins in normal and hyperlipidemic humans; (7) the intestine and high density lipoprotein (HDL) secretion in both experimental animals and man.